Characterization and Performance of Nano-La2O3 Prepared by Detonation Method
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摘要: 针对目前La2O3制备存在纯度低、烧结性差、分子间隙大等问题,发展纳米La2O3的新型制备方法显得尤为重要。以La(NO3)3·6H2O作为镧源加入乳化炸药中,通过乳化炸药爆轰反应为La2O3的合成提供高温高压条件,采用爆轰法在0.5 kg TNT当量真空爆炸容器内制备稀土纳米La2O3粉末。爆轰产物提纯、煅烧后,通过X射线衍射、扫描电子显微镜、傅里叶变换红外光谱进行产物的物相、形貌、成分表征,采用紫外-可见光光谱、氮气吸附-脱附等温线、CO2-程序升温脱附和O2-程序升温脱附进行性能测定,结果表明:煅烧温度对La2O3粉体的结晶生长具有显著影响;在煅烧温度为800 ℃、煅烧时间为3 h的条件下成功制备出吸收紫外光、纯净且分散性较好的纳米La2O3粉末,其粒径在50~175 nm区间,晶体结构为六方晶系;纳米La2O3的比表面积为17.46 m2/g,孔道有序性较好,且孔径分布集中,具有较好的酸性气体吸附能力和氧迁移性能。爆轰法应用于纳米La2O3粉末制备,为纳米La2O3的工业化制备提供了一种新的参考方法。Abstract: It is very important that new preparation method of nano-lanthanum oxide is explored in view of the current problems of low purity, poor sinterability, and large molecular gaps. Detonation method was employed to prepare rare earth nano-La2O3 powder in this study. La(NO3)3·6H2O was added to the emulsion explosive as a lanthanum source, and the high temperature and high pressure conditions for the synthesis of La2O3 were provided by the detonation reaction of the emulsion explosive in a 0.5 kg TNT equivalent vacuum explosion container. The physical phases, morphologies and ingredients of the purified and forged products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and the powder performances were determined by ultraviolet-visible spectroscopy (UV-Vis), Brunauer Emmett Teller (BET), CO2-temperature programmed desorption (CO2-TPD) and O2-temperature programmed desorption (O2-TPD). The results show that the forging temperature has a significant effect on the crystalline growth of La2O3 powder. Nano-La2O3 powder with high ultraviolet light absorption, high purity and good dispersion was successfully produced at a forging temperature of 800 ℃ and a forging time of 3 h. The particle size is in the range of 50-175 nm, and the crystal has a hexagonal structure. The specific surface area of the nano-La2O3 is 17.46 m2/g, with a good pore order and concentrated pore size distribution. The nano-La2O3 has good adsorption of acid gas and oxygen migration performance. The detonation method applied to the preparation process of nano-La2O3 powder provides a new reference for the industrial preparation of nano-La2O3.
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Key words:
- emulsion explosive /
- detonation method /
- rare earth /
- nano-La2O3 /
- adsorption
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表 1 专用乳化炸药配方设计
Table 1. Formulation design of specialised emulsified explosive
No. Mass fraction/% Oxygen balance NH4NO3 La(NO3)3·6H2O H2O Emulsifiers Composite wax 1 81 5 8 2 4 −0.0061 2 76 10 8 2 4 0.0024 3 71 15 8 2 4 0.0109 4 66 20 8 2 4 0.0194 表 2 专用乳化炸药爆炸的实验结果
Table 2. Pre-experimental results of specialized emulsion explosives
No. Explosive transmission
abilityAverage burst speed/(cm·s−1) 1 Full explosion 4015.1 2 Full explosion 4247.9 3 Full explosion 4513.5 4 Explosion rejection 表 3 混合炸药及爆轰产物的热化学参数[19]
Table 3. Thermochemical parameters of composite explosives and detonation products[19]
Molecular formula M/(g·mol−1) ΔHm/(kJ·mol−1) Molecular formula M/(g·mol−1) ΔHm/(kJ·mol−1) NH4NO3 80 −353.5 H2O(l) 18 −286.1 La(NO3)3·6H2O 433 −3887.3 H2O(g) 18 −241.8 C18H38 254 −558.0 CO2 44 −393.5 C24H44O6 428 −1333.9 CO 28 −110.5 La2O3 172 −1089.9 N2 28 0 表 4 不同热处理温度下纳米La2O3表面的性能参数
Table 4. Performance parameters of nano-La2O3 surfaces under different heat treatment temperatures
Sample SBET/(m2·g−1) Vpore/(cm3·g−1) Pore diameter/nm 1 16.5194 0.124929 27.7599 2 17.4581 0.146736 31.0622 3 16.9762 0.103253 32.9184 -
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